Turbine blade

Abstract

A turbine blade 29 for a gas turbine engine 10 having an axis 20 , the turbine blade 29 comprising: an aerofoil 30 including a high pressure surface 36 , a low pressure surface 34 , a root portion 38 and a tip surface 40 extending transverse from the high and low pressure surfaces 36 and 34 , the high and low pressure surfaces 36 and 34 curve from the root portion 38 to the tip surface 40 in a direction that is substantially tangential to the axis 20 of the engine 10 ; and an air leakage restricting member 32 on the tip surface 40 , the air leakage restricting member 32 being configured to substantially prevent leakage of air over the tip surface 40.

1. A turbine blade for a gas turbine engine having an axis from an intake of the engine to the exhaust of the engine, the turbine blade extending in a radial direction from the axis, the turbine blade comprising:
 an aerofoil including a high-pressure surface, a low pressure surface, a leading edge, a trailing edge, a root portion and a tip surface extending between the high and low pressure surfaces; and 
 an air leakage restricting member on the tip surface, the air leakage restricting member being configured to substantially prevent leakage of air over the tip surface, 
 wherein the leading edge curves from the root portion to the tip surface, in a direction that is substantially tangential to the axis of the engine, and the trailing edge is substantially straight, 
 wherein the curvature of the leading edge increases from the root portion to the tip surface, and 
 wherein the air leakage restricting member comprises a high pressure surface and a low pressure surface, extending between a leading edge of the air leakage restricting member and a trailing edge of the air leakage restricting member, at least a portion of the high pressure surface being one of substantially planar and convex and at least a portion of the low pressure surface being one of substantially planar and concave. 
 
   
   
     2. A turbine blade as claimed in  claim 1 , wherein the air leakage restricting member comprises a radially outer surface extending between the high and low pressure surfaces of the air leakage restricting member and having a surface area greater than a surface area of the tip surface so that the air leakage restricting member overhangs the aerofoil. 
   
   
     3. A turbine blade as claimed in  claim 2 , wherein the radially outer surface has an edge that coincides with an edge of the tip surface, along at least a portion of the high pressure surface of the air leakage restricting member, at the leading edge of the aerofoil. 
   
   
     4. A turbine blade as claimed in  claim 2 , wherein the air leakage restricting member has a region of greatest overhang, said region being along the high pressure surface of the aerofoil at a trailing edge region of the aerofoil. 
   
   
     5. A turbine blade as claimed in  claim 1 , wherein the air leakage restricting member comprises a channel extending between a leading edge of the air leakage restricting member and a trailing edge of the air leakage restricting member, for receiving air leaking over the radially outer surface. 
   
   
     6. A turbine blade as claimed in  claim 5 , wherein, in use, the direction of the air exiting the channel is different to the direction of the air leaving the trailing edge of the aerofoil. 
   
   
     7. A turbine blade as claimed in  claim 1 , wherein the air leakage restricting member comprises a plurality of conduits for receiving cooling air and arranged to provide the cooling air across the surfaces of the air leakage restricting member. 
   
   
     8. A turbine blade as claimed in  claim 1 , wherein the air leakage restricting member comprises a substantially straight trailing edge. 
   
   
     9. A turbine blade as claimed in  claim 1 , wherein the air leakage restriction member comprises at least one cavity for reducing the mass of the air leakage restricting member. 
   
   
     10. An arrangement of a plurality of turbine blades as claimed in  claim 1  for use in a gas turbine engine, wherein the minimum distance between adjacent air leakage restricting members is at a position between a leading edge and a trailing edge of each air leakage restricting member. 
   
   
     11. An air leakage restricting member for coupling to an aerofoil, the aerofoil comprising a high pressure surface, a low pressure surface, a leading edge, a trailing edge, a root portion and a tip surface extending between the high and low pressure surfaces, the leading edge curving from the root portion to the tip surface in a direction that is substantially tangential to an axis of a gas turbine engine and the trailing edge being substantially straight,
 wherein the air leakage restricting member is configured to substantially prevent leakage of air over the tip surface, and 
 wherein the curvature of the leading edge increases from the root portion to the tip surface. 
 
   
   
     12. An air leakage restricting member as claimed in  claim 11 , comprising a high pressure surface and a low pressure surface, extending between a leading edge of the air leakage restricting member and a trailing edge of the air leakage restricting member, at least a portion of the high pressure surface being one of substantially planar and convex and at least a portion of the low pressure surface being one of substantially planar and concave. 
   
   
     13. An air leakage restricting member as claimed in  claim 12 , comprising a radially outer surface extending between the high and low pressure surfaces and having a surface area greater than a surface area of the tip surface so that the air leakage restricting member overhangs the aerofoil. 
   
   
     14. An air leakage restricting member as claimed in  claim 13 , wherein the radially outer surface has an edge that coincides with an edge of the tip surface, along at least a portion of the high pressure surface of the air leakage restricting member, at a leading edge of the aerofoil. 
   
   
     15. An air leakage restricting member as claimed in  claim 11 , wherein the air leakage restricting member has a region of greatest overhang, said region being along the high pressure surface of the aerofoil at a trailing edge region of the aerofoil. 
   
   
     16. An air leakage restricting member as claimed in  claim 11 , comprising a channel extending between a leading edge of the air leakage restricting member and a trailing edge of the air leakage restricting member, for receiving air leaking over the radially outer surface. 
   
   
     17. An air leakage restricting member as claimed in  claim 16 , wherein, in use, the direction of air exiting the channel is different to the direction of air leaving the trailing edge of the aerofoil. 
   
   
     18. An air leakage restricting member as claimed in  claim 11 , comprising a plurality of conduits for receiving cooling air and arranged to provide the cooling air across the surfaces of the air leakage restricting member. 
   
   
     19. An air leakage restricting member as claimed in  claim 11 , comprising a substantially straight trailing edge. 
   
   
     20. An air leakage restricting member as claimed in  claim 11 , comprising at least one cavity for reducing the mass of the air leakage restricting member.